iMac G5 ( last generation with iSight) purchased in 2005 DEC without Intel chips in it ( The iMac with Intel chips launch on 2006 FEB ).In 2009 replaced Hard Disk to solve the unable to boot up problem.
In May 2011, Enough with the auto shutdown with chips over temperature and loud cooling fan sound. Re-apply heatsink compound by using the Cooler Master compound inbetween chips and cooler pad. After that restore the iMac then power it up.. WOW.. so quiet the cooling fan run in idle, no more in full speed , CPU temperature around 60 degree C only. even in multi application running the CPU temp. less than 80 degree C..
Dear Mayer, Can I deactivate the overheat sensors or components one by one to isolate the fault source. Need your suggestion to start somewhere. Do you think that I got faulty main circuit board. Thanks..